1. Technical Field
The present disclosure relates to a Power Factor Corrector, in particular, to a Power Factor Correction (PFC) boost converter applied in high efficiency switching power supply applications.
2. Description of Related Art
The growing awareness in environmental protection and the global warming issues have driven energy conservation to become a major policy agenda around the world. The U.S. Environmental Protection Agency (EPA) have adopted regulations that impose higher efficiency requirements on all types of electronic equipments to achieve the objective of energy saving. For instance, the basic 80 PLUS level requirement imposed on the PC power supply (80%, 80%, 80%), as well as certifications like 80 PLUS bronze (82%, 85%, 82%), 80 PLUS silver (85%, 88%, 85%), or 80 PLUS gold (87%, 90%, 87%). Hence increasing in power switching efficiency is a major current issue which we must overcome.
In the field of power electronics, the alternate current (AC) to direct current (DC) converters are widely applied. For examples, home appliances and computers all require the adaptation of the AC to DC converters to convert alternate current into direct current. As the current trend in the computer power supply industry moves toward high efficiency and high power factor, the power factor requirement has become increasingly rigorous in the modern power electronic circuit design. Due to the plurality of non-linear components used in the AC to DC converters, such as the bridge rectifier filters, it is necessary to employ Power Factor Corrector to adjust the phase of both the output voltage and the output current to increase the power factor. The most commonly-seen structure of this type is the Power Factor Correction boost converter.
Converters generally operate in the continuous conduction mode (CCM), and using average-current mode with fixed frequency control, to maintain the switching frequency of the power supply at a fixed value regardless of the load level of the output voltage. However, maintaining at a fixed switching frequency (at a high value, especially) is often undesirable when the switching power supply is only carrying light or medium loads, as it will increase switching loss, driver loss, and core loss of the power transistor, thus negatively affecting the conversion efficiency of the overall power supply. Therefore, how to reduce the power loss during the switching period of the power supply currently becomes an important research topic in field of power electronics.